One of the major difficulties faced in the integration of optoelectronic packages with printed wiring boards (PWB), is to couple efficiently the light between optoelectronic devices and optical waveguides provided on a PWB.
Several methods have been proposed to perform such integration in the case of optoelectronic packages that comprises a vertical cavity surface emitting laser (VCSEL), but most of them involve at some point the step of aligning a 45 degree mirror with respect to the VCSEL output in order to deflect the VCSEL light into an optical waveguide embedded into a PCB. FIG. 1b shows an example of such prior art embodiment where a VCSEL 13, mounted inside the cavity of a cavity down ball grid array (BGA) 22, is optically coupled to an embedded optical waveguide 18 by means of a 45 degree mirror 25 that was inserted and aligned inside the PWB 20. However, this alignment step is difficult to achieve and is thus time-consuming.
In another proposed method, illustrated in FIG. 1c, the integrated circuit IC package 12 includes a VCSEL 13 inserted into a PWB 20 recessed section for optical coupling to an embedded optical waveguide 18. A butterfly package 36, as shown in FIG. 1a, is another prior art embodiment where an optical fiber 19 was aligned to a laser output and then bonded to the package. Again, these prior art embodiments require an alignment step of the laser 13 with respect to the optical waveguide 18 or optical fiber 19 which remains a time-consuming process.
Recently, it was proposed by Rho et al. (J. Lightwave Technology, vol. 22, no. 9, 2004) to use a 45 degree ended optical connection rod as a medium to guide light emitted by the VCSEL toward an embedded optical waveguide of the PWB. However this method still comprises the step of aligning the rod with respect to the VCSEL and with respect to the embedded waveguide, which can be difficult and time consuming.